The invention is based on a tire-pressure regulating system. A system of this kind is known from German Auslegeschrift No. 26 30 511.
In this known system, a measurement of pressure per se takes place in the supply line. Since the pressure sensors either cannot be disposed in the vehicle wheels or can be so disposed only with great difficulty, the known regulating system necessarily requires a waiting period until a complete pressure equalization has taken place, before one can obtain some idea of the new pressure more recently attained. In other words, a maintenance function without any supply or withdrawal of air must be attained. Only then is it possible to effect follow-up regulation, and only after such an adjustment has brought about, the desired tire pressure can the supply line be bled, this bleeding being important in order to relieve the pressure on the rotor connections disposed on the wheels, and thus to reduce friction.
It is true that another known regulating system (German Auslegeschrift No. 27 36 603) is equipped with a timer switch which shuts off the pressure variation which has been determined empirically after a set period of time. However, there are various adjustment variables which change the filling time--for instance, the supply pressure at a particular time--and another factor is whether the compressor which feeds the supply container feeds air directly via this container into the tires, or not. For instance, if the vehicle has been shut off in the meantime and the equalization of pressure had not yet been completed upon vehicle shutoff, then after several such cycles, a shift in the pressure level in the tires takes place.
Finally, it is also already known from German Offenlegungsschrift No. 21 41 553 that the regulating process can be automatically interrupted via a timer switch once a certain tire pressure has been attained.